The Dengue Virus and Possibilities of Antiviral Treatment

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Introduction

Transmission electron micrograph of Dengue virus (the circular structures) taken by Frederick Murphy, Cynthia Goldsmith, USCDCP.


By Nicholas Vitale

The dengue virus is a mosquito borne RNA positive virus of the Flavivirus genus that causes dengue fever. This illness affects about 100 million individuals a year across the globe, is extremely prevalent in many underdeveloped tropical areas, and there is no known antiviral treatment for the virus. Due to the lack of treatment, the affected areas are forced to try to control the populations of mosquitoes that transmit the virus, which can be challenging. Due to the vast amount of people that this potentially fatal virus affects there has been a large amount of research in recent years focusing on the mode of the viral action and the different ways to fight it. Some research groups have had some success in stopping the viral action of dengue. For example, the Talarico et al. group had success in fighting the dengue virus using the antiviral activity of sulfated polysaccharides, but the effectiveness of the treatment depends on the serotype of the virus (of which there are 5). Clearly the viral activity of dengue is complex and not completely understood, but there are still many other possibilities for treatment of this illness.

History of Dengue Virus

Map of the spread of the Dengue virus from Messina et al.


The first isolation of the Dengue virus (DENV1) was found in 1943 in areas of the Southern Pacific region like the French Polynesian Islands and other land masses like Japan, but to date there have been four different isolates of the dengue virus found (2). After the discovery of DENV1 it was constantly rising in prevalence mainly in the Southern Asia region, which sparked the interest of researchers to learn more of the possibly fatal disease. With the increased interest in the virus three different types of isolates were found across the globe: in 1944 DENV2 was discovered in Indonesia, in 1953 DENV3 was discovered in Thailand, and DENV4 was also first discovered in Thailand (2). Much of the research into the newly prominent disease was sparked by the epidemics of dengue fever in the Philippines that occurred at various times throughout the 1950’s.

Despite the rather quick discovery of all different versions of the virus, it seemed that there was a relative drop off in the rise of reported cases of dengue fever, which lead to decreased interest in the research of the virus. Due to many different reasons such as increased air travel and lack of knowledge of the disease in the 1980’s there was a large increase in prevalence of the virus globally. Rather than being confined to the Southern Asia and Pacific ocean regions, the virus was seen to spread into Southern and Central America as well as more prominently in Asia affecting highly populated areas like India and China (Figure 2). This exponential growth seen of the Dengue viruses across the globe has not stopped and does not seem as if it is going to in the nearby future. The new reports of the disease are now being collected in a virus type specific manner, which is very important in order to understand and regulate the disease (more on this in “Epidemiology of Dengue Fever”).

Although today the disease is seen to be very prevalent in many warm highly populated regions of the globe it still may also be very present in similar but underdeveloped areas of the globe like central Africa (2). Researchers believe that being able to more fully obtain up-to-date reports from all areas of the globe affected by the Dengue viruses will increase the ability of the scientific community to understand and regulate the prevalence of the virus. The tracking of the disease has proven to show that all four types of Dengue virus have no trouble integrating into new lands where the disease has not yet been. This finding is rather foreboding as in our modern world of constant transportation microbes from foreign lands are constantly being introduced into new areas and the Dengue viruses have shown that they can thrive under these circumstances. Further, the tracking of the spread of this mosquito borne disease will have important implications for ongoing research. With this knowledge it is very important to continue to track the spread of Dengue viruses in order to understand, detect, and react to the growing burden of the viruses.

Most recently, a new serotype of the Dengue virus has been found making it so that there are now five phylogenetically different strains of the virus (3). The discovery occurred in 2013 by researchers in Bangkok. This throws a very large hook into all of the ongoing research of the disease and possibilities of immunizations. This news is especially devastating considering that an immunization for the four known serotypes of the Dengue virus was about to undergo clinical trial late in 2012 (3). The discovery of this new serotype puts a large burden on the researchers of the virus. Since there is no anti-viral or drug remedy for the disease the discovery of a new serotype pushes back all the researchers that have been attempting to create immunizations and other remedies many years.

Section 2

Include some current research, with at least one figure showing data.

Section 3

Images of the medicinal plants proposed to have inhibitory effects on the pathogenic action of Dengue virus by Frederico et al.. Vernonia cinerea (right) and Tridax procumbers (left).

Include some current research, with at least one figure showing data.

Section 4

Conclusion

References



Authored for BIOL 238 Microbiology, taught by Joan Slonczewski, 2018, Kenyon College.